love2d.love/src/modules/graphics/opengl/Shader.cpp

/**
 * Copyright (c) 2006-2020 LOVE Development Team
 *
 * This software is provided 'as-is', without any express or implied
 * warranty.  In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 **/

// LOVE
#include "common/config.h"

#include "Shader.h"
#include "ShaderStage.h"
#include "Graphics.h"
#include "graphics/vertex.h"

// C++
#include <algorithm>
#include <limits>
#include <sstream>

namespace love
{
namespace graphics
{
namespace opengl
{

Shader::Shader(love::graphics::ShaderStage *vertex, love::graphics::ShaderStage *pixel)
	: love::graphics::Shader(vertex, pixel)
	, program(0)
	, builtinUniforms()
	, builtinUniformInfo()
	, lastPointSize(0.0f)
{
	// load shader source and create program object
	loadVolatile();
}

Shader::~Shader()
{
	unloadVolatile();

	for (const auto &p : uniforms)
	{
		// Allocated with malloc().
		if (p.second.data != nullptr)
			free(p.second.data);

		if (p.second.baseType == UNIFORM_SAMPLER)
		{
			for (int i = 0; i < p.second.count; i++)
			{
				if (p.second.textures[i] != nullptr)
					p.second.textures[i]->release();
			}

			delete[] p.second.textures;
		}
		else if (p.second.baseType == UNIFORM_TEXELBUFFER)
		{
			for (int i = 0; i < p.second.count; i++)
			{
				if (p.second.buffers[i] != nullptr)
					p.second.buffers[i]->release();
			}

			delete[] p.second.buffers;
		}
	}
}

void Shader::mapActiveUniforms()
{
	// Built-in uniform locations default to -1 (nonexistent.)
	for (int i = 0; i < int(BUILTIN_MAX_ENUM); i++)
	{
		builtinUniforms[i] = -1;
		builtinUniformInfo[i] = nullptr;
	}

	GLint activeprogram = 0;
	glGetIntegerv(GL_CURRENT_PROGRAM, &activeprogram);

	gl.useProgram(program);

	GLint numuniforms;
	glGetProgramiv(program, GL_ACTIVE_UNIFORMS, &numuniforms);

	GLchar cname[256];
	const GLint bufsize = (GLint) (sizeof(cname) / sizeof(GLchar));

	std::map<std::string, UniformInfo> olduniforms = uniforms;
	uniforms.clear();

	for (int uindex = 0; uindex < numuniforms; uindex++)
	{
		GLsizei namelen = 0;
		GLenum gltype = 0;
		UniformInfo u = {};

		glGetActiveUniform(program, (GLuint) uindex, bufsize, &namelen, &u.count, &gltype, cname);

		u.name = std::string(cname, (size_t) namelen);
		u.location = glGetUniformLocation(program, u.name.c_str());
		u.baseType = getUniformBaseType(gltype);
		u.textureType = getUniformTextureType(gltype);
		u.texelBufferType = getUniformTexelBufferType(gltype);
		u.isDepthSampler = isDepthTextureType(gltype);

		if (u.baseType == UNIFORM_MATRIX)
			u.matrix = getMatrixSize(gltype);
		else
			u.components = getUniformTypeComponents(gltype);

		// glGetActiveUniform appends "[0]" to the end of array uniform names...
		if (u.name.length() > 3)
		{
			size_t findpos = u.name.find("[0]");
			if (findpos != std::string::npos && findpos == u.name.length() - 3)
				u.name.erase(u.name.length() - 3);
		}

		// If this is a built-in (LOVE-created) uniform, store the location.
		BuiltinUniform builtin = BUILTIN_MAX_ENUM;
		if (getConstant(u.name.c_str(), builtin))
			builtinUniforms[int(builtin)] = u.location;

		if (u.location == -1)
			continue;

		if ((u.baseType == UNIFORM_SAMPLER && builtin != BUILTIN_TEXTURE_MAIN) || u.baseType == UNIFORM_TEXELBUFFER)
		{
			TextureUnit unit;
			unit.type = u.textureType;
			unit.active = true;

			if (u.baseType == UNIFORM_TEXELBUFFER)
			{
				unit.isTexelBuffer = true;
				unit.texture = gl.getDefaultTexelBuffer();
			}
			else
			{
				unit.isTexelBuffer = false;
				unit.texture = gl.getDefaultTexture(u.textureType);
			}

			for (int i = 0; i < u.count; i++)
				textureUnits.push_back(unit);
		}

		// Make sure previously set uniform data is preserved, and shader-
		// initialized values are retrieved.
		auto oldu = olduniforms.find(u.name);
		if (oldu != olduniforms.end())
		{
			u.data = oldu->second.data;
			u.dataSize = oldu->second.dataSize;
			u.textures = oldu->second.textures;

			updateUniform(&u, u.count, true);
		}
		else
		{
			u.dataSize = 0;

			switch (u.baseType)
			{
			case UNIFORM_FLOAT:
				u.dataSize = sizeof(float) * u.components * u.count;
				u.data = malloc(u.dataSize);
				break;
			case UNIFORM_INT:
			case UNIFORM_BOOL:
			case UNIFORM_SAMPLER:
			case UNIFORM_TEXELBUFFER:
				u.dataSize = sizeof(int) * u.components * u.count;
				u.data = malloc(u.dataSize);
				break;
			case UNIFORM_UINT:
				u.dataSize = sizeof(unsigned int) * u.components * u.count;
				u.data = malloc(u.dataSize);
				break;
			case UNIFORM_MATRIX:
				u.dataSize = sizeof(float) * (u.matrix.rows * u.matrix.columns) * u.count;
				u.data = malloc(u.dataSize);
				break;
			default:
				break;
			}

			if (u.dataSize > 0)
			{
				memset(u.data, 0, u.dataSize);

				if (u.baseType == UNIFORM_SAMPLER || u.baseType == UNIFORM_TEXELBUFFER)
				{
					int startunit = (int) textureUnits.size() - u.count;

					if (builtin == BUILTIN_TEXTURE_MAIN)
						startunit = 0;

					for (int i = 0; i < u.count; i++)
						u.ints[i] = startunit + i;

					glUniform1iv(u.location, u.count, u.ints);

					if (u.baseType == UNIFORM_TEXELBUFFER)
					{
						u.buffers = new love::graphics::Buffer*[u.count];
						memset(u.buffers, 0, sizeof(Buffer *) * u.count);
					}
					else
					{
						u.textures = new love::graphics::Texture*[u.count];
						memset(u.textures, 0, sizeof(Texture *) * u.count);
					}
				}
			}

			size_t offset = 0;

			// Store any shader-initialized values in our own memory.
			for (int i = 0; i < u.count; i++)
			{
				GLint location = u.location;

				if (u.count > 1)
				{
					std::ostringstream ss;
					ss << i;

					std::string indexname = u.name + "[" + ss.str() + "]";
					location = glGetUniformLocation(program, indexname.c_str());
				}

				if (location == -1)
					continue;

				switch (u.baseType)
				{
				case UNIFORM_FLOAT:
					glGetUniformfv(program, location, &u.floats[offset]);
					offset += u.components;
					break;
				case UNIFORM_INT:
				case UNIFORM_BOOL:
					glGetUniformiv(program, location, &u.ints[offset]);
					offset += u.components;
					break;
				case UNIFORM_UINT:
					glGetUniformuiv(program, location, &u.uints[offset]);
					offset += u.components;
					break;
				case UNIFORM_MATRIX:
					glGetUniformfv(program, location, &u.floats[offset]);
					offset += u.matrix.rows * u.matrix.columns;
					break;
				default:
					break;
				}
			}
		}

		uniforms[u.name] = u;

		if (builtin != BUILTIN_MAX_ENUM)
			builtinUniformInfo[(int)builtin] = &uniforms[u.name];

		if (u.baseType == UNIFORM_SAMPLER)
		{
			// Make sure all stored textures have their Volatiles loaded before
			// the sendTextures call, since it calls getHandle().
			for (int i = 0; i < u.count; i++)
			{
				if (u.textures[i] == nullptr)
					continue;
				Volatile *v = dynamic_cast<Volatile *>(u.textures[i]);
				if (v != nullptr)
					v->loadVolatile();
			}

			sendTextures(&u, u.textures, u.count, true);
		}
		else if (u.baseType == UNIFORM_TEXELBUFFER)
		{
			for (int i = 0; i < u.count; i++)
			{
				if (u.buffers[i] == nullptr)
					continue;
				Volatile *v = dynamic_cast<Volatile *>(u.buffers[i]);
				if (v != nullptr)
					v->loadVolatile();
			}

			sendBuffers(&u, u.buffers, u.count, true);
		}
	}

	// Make sure uniforms that existed before but don't exist anymore are
	// cleaned up. This theoretically shouldn't happen, but...
	for (const auto &p : olduniforms)
	{
		if (uniforms.find(p.first) == uniforms.end())
		{
			free(p.second.data);

			if (p.second.baseType == UNIFORM_SAMPLER)
			{
				for (int i = 0; i < p.second.count; i++)
				{
					if (p.second.textures[i] != nullptr)
						p.second.textures[i]->release();
				}

				delete[] p.second.textures;
			}
			else if (p.second.baseType == UNIFORM_TEXELBUFFER)
			{
				for (int i = 0; i < p.second.count; i++)
				{
					if (p.second.buffers[i] != nullptr)
						p.second.buffers[i]->release();
				}

				delete[] p.second.buffers;
			}
		}
	}

	gl.useProgram(activeprogram);
}

bool Shader::loadVolatile()
{
	OpenGL::TempDebugGroup debuggroup("Shader load");

	lastPointSize = -1.0f;

	// zero out active texture list
	textureUnits.clear();
	textureUnits.push_back(TextureUnit());

	for (const auto &stage : stages)
	{
		if (stage.get() != nullptr)
			((ShaderStage*)stage.get())->loadVolatile();
	}

	program = glCreateProgram();

	if (program == 0)
		throw love::Exception("Cannot create shader program object.");

	for (const auto &stage : stages)
	{
		if (stage.get() != nullptr)
			glAttachShader(program, (GLuint) stage->getHandle());
	}

	// Bind generic vertex attribute indices to names in the shader.
	for (int i = 0; i < int(ATTRIB_MAX_ENUM); i++)
	{
		const char *name = nullptr;
		if (graphics::getConstant((BuiltinVertexAttribute) i, name))
			glBindAttribLocation(program, i, (const GLchar *) name);
	}

	glLinkProgram(program);

	GLint status;
	glGetProgramiv(program, GL_LINK_STATUS, &status);

	if (status == GL_FALSE)
	{
		std::string warnings = getProgramWarnings();
		glDeleteProgram(program);
		program = 0;
		throw love::Exception("Cannot link shader program object:\n%s", warnings.c_str());
	}

	// Get all active uniform variables in this shader from OpenGL.
	mapActiveUniforms();

	if (current == this)
	{
		// make sure glUseProgram gets called.
		current = nullptr;
		attach();
	}

	return true;
}

void Shader::unloadVolatile()
{
	if (program != 0)
	{
		if (current == this)
			gl.useProgram(0);

		glDeleteProgram(program);
		program = 0;
	}

	// active texture list is probably invalid, clear it
	textureUnits.clear();
	textureUnits.push_back(TextureUnit());

	attributes.clear();

	// And the locations of any built-in uniform variables.
	for (int i = 0; i < int(BUILTIN_MAX_ENUM); i++)
		builtinUniforms[i] = -1;
}

std::string Shader::getProgramWarnings() const
{
	GLint strsize, nullpos;
	glGetProgramiv(program, GL_INFO_LOG_LENGTH, &strsize);

	if (strsize == 0)
		return "";

	char *tempstr = new char[strsize];
	// be extra sure that the error string will be 0-terminated
	memset(tempstr, '\0', strsize);
	glGetProgramInfoLog(program, strsize, &nullpos, tempstr);
	tempstr[nullpos] = '\0';

	std::string warnings(tempstr);
	delete[] tempstr;

	return warnings;
}

std::string Shader::getWarnings() const
{
	std::string warnings;
	const char *stagestr;

	for (const auto &stage : stages)
	{
		if (stage.get() == nullptr)
			continue;

		const std::string &stagewarnings = stage->getWarnings();

		if (ShaderStage::getConstant(stage->getStageType(), stagestr))
			warnings += std::string(stagestr) + std::string(" shader:\n") + stagewarnings;
	}

	warnings += getProgramWarnings();

	return warnings;
}

void Shader::attach()
{
	if (current != this)
	{
		Graphics::flushBatchedDrawsGlobal();

		gl.useProgram(program);
		current = this;
		// retain/release happens in Graphics::setShader.

		// Make sure all textures are bound to their respective texture units.
		for (int i = 0; i < (int) textureUnits.size(); ++i)
		{
			const TextureUnit &unit = textureUnits[i];
			if (unit.active)
			{
				if (unit.isTexelBuffer)
					gl.bindBufferTextureToUnit(unit.texture, i, false, false);
				else
					gl.bindTextureToUnit(unit.type, unit.texture, i, false, false);
			}
		}

		// send any pending uniforms to the shader program.
		for (const auto &p : pendingUniformUpdates)
			updateUniform(p.first, p.second, true);

		pendingUniformUpdates.clear();
	}
}

const Shader::UniformInfo *Shader::getUniformInfo(const std::string &name) const
{
	const auto it = uniforms.find(name);

	if (it == uniforms.end())
		return nullptr;

	return &(it->second);
}

const Shader::UniformInfo *Shader::getUniformInfo(BuiltinUniform builtin) const
{
	return builtinUniformInfo[(int)builtin];
}

void Shader::updateUniform(const UniformInfo *info, int count)
{
	updateUniform(info, count, false);
}

void Shader::updateUniform(const UniformInfo *info, int count, bool internalupdate)
{
	if (current != this && !internalupdate)
	{
		pendingUniformUpdates.push_back(std::make_pair(info, count));
		return;
	}

	if (!internalupdate)
		flushBatchedDraws();

	int location = info->location;
	UniformType type = info->baseType;

	if (type == UNIFORM_FLOAT)
	{
		switch (info->components)
		{
		case 1:
			glUniform1fv(location, count, info->floats);
			break;
		case 2:
			glUniform2fv(location, count, info->floats);
			break;
		case 3:
			glUniform3fv(location, count, info->floats);
			break;
		case 4:
			glUniform4fv(location, count, info->floats);
			break;
		}
	}
	else if (type == UNIFORM_INT || type == UNIFORM_BOOL || type == UNIFORM_SAMPLER || type == UNIFORM_TEXELBUFFER)
	{
		switch (info->components)
		{
		case 1:
			glUniform1iv(location, count, info->ints);
			break;
		case 2:
			glUniform2iv(location, count, info->ints);
			break;
		case 3:
			glUniform3iv(location, count, info->ints);
			break;
		case 4:
			glUniform4iv(location, count, info->ints);
			break;
		}
	}
	else if (type == UNIFORM_UINT)
	{
		switch (info->components)
		{
		case 1:
			glUniform1uiv(location, count, info->uints);
			break;
		case 2:
			glUniform2uiv(location, count, info->uints);
			break;
		case 3:
			glUniform3uiv(location, count, info->uints);
			break;
		case 4:
			glUniform4uiv(location, count, info->uints);
			break;
		}
	}
	else if (type == UNIFORM_MATRIX)
	{
		int columns = info->matrix.columns;
		int rows = info->matrix.rows;

		if (columns == 2 && rows == 2)
			glUniformMatrix2fv(location, count, GL_FALSE, info->floats);
		else if (columns == 3 && rows == 3)
			glUniformMatrix3fv(location, count, GL_FALSE, info->floats);
		else if (columns == 4 && rows == 4)
			glUniformMatrix4fv(location, count, GL_FALSE, info->floats);
		else if (columns == 2 && rows == 3)
			glUniformMatrix2x3fv(location, count, GL_FALSE, info->floats);
		else if (columns == 2 && rows == 4)
			glUniformMatrix2x4fv(location, count, GL_FALSE, info->floats);
		else if (columns == 3 && rows == 2)
			glUniformMatrix3x2fv(location, count, GL_FALSE, info->floats);
		else if (columns == 3 && rows == 4)
			glUniformMatrix3x4fv(location, count, GL_FALSE, info->floats);
		else if (columns == 4 && rows == 2)
			glUniformMatrix4x2fv(location, count, GL_FALSE, info->floats);
		else if (columns == 4 && rows == 3)
			glUniformMatrix4x3fv(location, count, GL_FALSE, info->floats);
	}
}

void Shader::sendTextures(const UniformInfo *info, love::graphics::Texture **textures, int count)
{
	Shader::sendTextures(info, textures, count, false);
}

void Shader::sendTextures(const UniformInfo *info, love::graphics::Texture **textures, int count, bool internalUpdate)
{
	if (info->baseType != UNIFORM_SAMPLER)
		return;

	bool shaderactive = current == this;

	if (!internalUpdate && shaderactive)
		flushBatchedDraws();

	count = std::min(count, info->count);

	// Bind the textures to the texture units.
	for (int i = 0; i < count; i++)
	{
		love::graphics::Texture *tex = textures[i];

		if (tex != nullptr)
		{
			const SamplerState &sampler = tex->getSamplerState();
			if (!tex->isReadable())
			{
				if (internalUpdate)
					continue;
				else
					throw love::Exception("Textures with non-readable formats cannot be sampled from in a shader.");
			}
			else if (info->isDepthSampler != sampler.depthSampleMode.hasValue)
			{
				if (internalUpdate)
					continue;
				else if (info->isDepthSampler)
					throw love::Exception("Depth comparison samplers in shaders can only be used with depth textures which have depth comparison set.");
				else
					throw love::Exception("Depth textures which have depth comparison set can only be used with depth/shadow samplers in shaders.");
			}
			else if (tex->getTextureType() != info->textureType)
			{
				if (internalUpdate)
					continue;
				else
				{
					const char *textypestr = "unknown";
					const char *shadertextypestr = "unknown";
					Texture::getConstant(tex->getTextureType(), textypestr);
					Texture::getConstant(info->textureType, shadertextypestr);
					throw love::Exception("Texture's type (%s) must match the type of %s (%s).", textypestr, info->name.c_str(), shadertextypestr);
				}
			}

			tex->retain();
		}

		if (info->textures[i] != nullptr)
			info->textures[i]->release();

		info->textures[i] = tex;

		GLuint gltex = 0;
		if (textures[i] != nullptr)
			gltex = (GLuint) tex->getHandle();
		else
			gltex = gl.getDefaultTexture(info->textureType);

		int texunit = info->ints[i];

		if (shaderactive)
			gl.bindTextureToUnit(info->textureType, gltex, texunit, false, false);

		// Store texture id so it can be re-bound to the texture unit later.
		textureUnits[texunit].texture = gltex;
	}
}

void Shader::sendBuffers(const UniformInfo *info, love::graphics::Buffer **buffers, int count)
{
	Shader::sendBuffers(info, buffers, count, false);
}

static bool isTexelBufferTypeCompatible(DataBaseType a, DataBaseType b)
{
	if (a == DATA_BASETYPE_FLOAT || a == DATA_BASETYPE_UNORM || a == DATA_BASETYPE_SNORM)
		return b == DATA_BASETYPE_FLOAT || b == DATA_BASETYPE_UNORM || b == DATA_BASETYPE_SNORM;

	if (a == DATA_BASETYPE_INT && b == DATA_BASETYPE_INT)
		return true;

	if (a == DATA_BASETYPE_UINT && b == DATA_BASETYPE_UINT)
		return true;

	return false;
}

void Shader::sendBuffers(const UniformInfo *info, love::graphics::Buffer **buffers, int count, bool internalUpdate)
{
	if (info->baseType != UNIFORM_TEXELBUFFER)
		return;

	uint32 requiredtypeflags = Buffer::TYPEFLAG_TEXEL;

	bool shaderactive = current == this;

	if (!internalUpdate && shaderactive)
		flushBatchedDraws();

	count = std::min(count, info->count);

	// Bind the textures to the texture units.
	for (int i = 0; i < count; i++)
	{
		love::graphics::Buffer *buffer = buffers[i];

		if (buffer != nullptr)
		{
			if ((buffer->getTypeFlags() & requiredtypeflags) == 0)
			{
				if (internalUpdate)
					continue;
				else
					throw love::Exception("Shader uniform '%s' is a texel buffer, but the given Buffer was not created with texel buffer capabilities.", info->name.c_str());
			}

			DataBaseType basetype = buffer->getDataMember(0).info.baseType;
			if (!isTexelBufferTypeCompatible(basetype, info->texelBufferType))
			{
				if (internalUpdate)
					continue;
				else
					throw love::Exception("Texel buffer's data format base type must match the variable declared in the shader.");
			}

			buffer->retain();
		}

		bool addbuffertoarray = true;

		if (info->buffers[i] != nullptr)
		{
			Buffer *oldbuffer = info->buffers[i];
			auto it = std::find(buffersToUnmap.begin(), buffersToUnmap.end(), oldbuffer);
			if (it != buffersToUnmap.end())
			{
				addbuffertoarray = false;
				if (buffer != nullptr)
					*it = buffer;
				else
				{
					auto last = buffersToUnmap.end() - 1;
					*it = *last;
					buffersToUnmap.erase(last);
				}
			}

			oldbuffer->release();
		}

		if (addbuffertoarray && buffer != nullptr)
			buffersToUnmap.push_back(buffer);

		info->buffers[i] = buffer;

		GLuint gltex = 0;
		if (buffers[i] != nullptr)
			gltex = (GLuint) buffer->getTexelBufferHandle();
		else
			gltex = gl.getDefaultTexelBuffer();

		int texunit = info->ints[i];

		if (shaderactive)
			gl.bindBufferTextureToUnit(gltex, texunit, false, false);

		// Store texture id so it can be re-bound to the texture unit later.
		textureUnits[texunit].texture = gltex;
	}
}

void Shader::flushBatchedDraws() const
{
	if (current == this)
		Graphics::flushBatchedDrawsGlobal();
}

bool Shader::hasUniform(const std::string &name) const
{
	return uniforms.find(name) != uniforms.end();
}

ptrdiff_t Shader::getHandle() const
{
	return program;
}

int Shader::getVertexAttributeIndex(const std::string &name)
{
	auto it = attributes.find(name);
	if (it != attributes.end())
		return it->second;

	GLint location = glGetAttribLocation(program, name.c_str());

	attributes[name] = location;
	return location;
}

void Shader::setVideoTextures(love::graphics::Texture *ytexture, love::graphics::Texture *cbtexture, love::graphics::Texture *crtexture)
{
	const BuiltinUniform builtins[3] = {
		BUILTIN_TEXTURE_VIDEO_Y,
		BUILTIN_TEXTURE_VIDEO_CB,
		BUILTIN_TEXTURE_VIDEO_CR,
	};

	love::graphics::Texture *textures[3] = {ytexture, cbtexture, crtexture};

	for (int i = 0; i < 3; i++)
	{
		const UniformInfo *info = builtinUniformInfo[builtins[i]];

		if (info != nullptr)
			sendTextures(info, &textures[i], 1, true);
	}
}

void Shader::updatePointSize(float size)
{
	if (size == lastPointSize || current != this)
		return;

	GLint location = builtinUniforms[BUILTIN_POINT_SIZE];
	if (location >= 0)
		glUniform1f(location, size);

	lastPointSize = size;
}

void Shader::updateBuiltinUniforms(love::graphics::Graphics *gfx, int viewportW, int viewportH)
{
	if (current != this)
		return;

	if (GLAD_ES_VERSION_2_0)
		updatePointSize(gl.getPointSize());

	BuiltinUniformData data;

	data.transformMatrix = gfx->getTransform();
	data.projectionMatrix = gfx->getProjection();

	// The normal matrix is the transpose of the inverse of the rotation portion
	// (top-left 3x3) of the transform matrix.
	{
		Matrix3 normalmatrix = Matrix3(data.transformMatrix).transposedInverse();
		const float *e = normalmatrix.getElements();
		for (int i = 0; i < 3; i++)
		{
			data.normalMatrix[i].x = e[i * 3 + 0];
			data.normalMatrix[i].y = e[i * 3 + 1];
			data.normalMatrix[i].z = e[i * 3 + 2];
			data.normalMatrix[i].w = 0.0f;
		}
	}

	data.screenSizeParams.x = viewportW;
	data.screenSizeParams.y = viewportH;

	// The shader does pixcoord.y = gl_FragCoord.y * params.z + params.w.
	// This lets us flip pixcoord.y when needed, to be consistent (drawing
	// with no RT active makes the pixel coordinates y-flipped.)
	if (gfx->isRenderTargetActive())
	{
		// No flipping: pixcoord.y = gl_FragCoord.y * 1.0 + 0.0.
		data.screenSizeParams.z = 1.0f;
		data.screenSizeParams.w = 0.0f;
	}
	else
	{
		// gl_FragCoord.y is flipped when drawing to the screen, so we
		// un-flip: pixcoord.y = gl_FragCoord.y * -1.0 + height.
		data.screenSizeParams.z = -1.0f;
		data.screenSizeParams.w = viewportH;
	}

	data.constantColor = gfx->getColor();
	gammaCorrectColor(data.constantColor);

	GLint location = builtinUniforms[BUILTIN_UNIFORMS_PER_DRAW];
	if (location >= 0)
		glUniform4fv(location, 13, (const GLfloat *) &data);

	// TODO: Find a better place to put this.
	// Buffers used in this shader can be mapped by external code without
	// unmapping. We need to make sure the data on the GPU is up to date,
	// otherwise the shader can read from old data.
	for (Buffer *buffer : buffersToUnmap)
		buffer->unmap();
}

int Shader::getUniformTypeComponents(GLenum type) const
{
	UniformType basetype = getUniformBaseType(type);

	if (basetype == UNIFORM_SAMPLER || basetype == UNIFORM_TEXELBUFFER)
		return 1;

	switch (type)
	{
	case GL_INT:
	case GL_UNSIGNED_INT:
	case GL_FLOAT:
	case GL_BOOL:
		return 1;
	case GL_INT_VEC2:
	case GL_UNSIGNED_INT_VEC2:
	case GL_FLOAT_VEC2:
	case GL_FLOAT_MAT2:
	case GL_BOOL_VEC2:
		return 2;
	case GL_INT_VEC3:
	case GL_UNSIGNED_INT_VEC3:
	case GL_FLOAT_VEC3:
	case GL_FLOAT_MAT3:
	case GL_BOOL_VEC3:
		return 3;
	case GL_INT_VEC4:
	case GL_UNSIGNED_INT_VEC4:
	case GL_FLOAT_VEC4:
	case GL_FLOAT_MAT4:
	case GL_BOOL_VEC4:
		return 4;
	default:
		return 1;
	}
}

Shader::MatrixSize Shader::getMatrixSize(GLenum type) const
{
	MatrixSize m;

	switch (type)
	{
	case GL_FLOAT_MAT2:
		m.columns = m.rows = 2;
		break;
	case GL_FLOAT_MAT3:
		m.columns = m.rows = 3;
		break;
	case GL_FLOAT_MAT4:
		m.columns = m.rows = 4;
		break;
	case GL_FLOAT_MAT2x3:
		m.columns = 2;
		m.rows = 3;
		break;
	case GL_FLOAT_MAT2x4:
		m.columns = 2;
		m.rows = 4;
		break;
	case GL_FLOAT_MAT3x2:
		m.columns = 3;
		m.rows = 2;
		break;
	case GL_FLOAT_MAT3x4:
		m.columns = 3;
		m.rows = 4;
		break;
	case GL_FLOAT_MAT4x2:
		m.columns = 4;
		m.rows = 2;
		break;
	case GL_FLOAT_MAT4x3:
		m.columns = 4;
		m.rows = 3;
		break;
	}

	return m;
}

Shader::UniformType Shader::getUniformBaseType(GLenum type) const
{
	switch (type)
	{
	case GL_INT:
	case GL_INT_VEC2:
	case GL_INT_VEC3:
	case GL_INT_VEC4:
		return UNIFORM_INT;
	case GL_UNSIGNED_INT:
	case GL_UNSIGNED_INT_VEC2:
	case GL_UNSIGNED_INT_VEC3:
	case GL_UNSIGNED_INT_VEC4:
		return UNIFORM_UINT;
	case GL_FLOAT:
	case GL_FLOAT_VEC2:
	case GL_FLOAT_VEC3:
	case GL_FLOAT_VEC4:
		return UNIFORM_FLOAT;
	case GL_FLOAT_MAT2:
	case GL_FLOAT_MAT3:
	case GL_FLOAT_MAT4:
	case GL_FLOAT_MAT2x3:
	case GL_FLOAT_MAT2x4:
	case GL_FLOAT_MAT3x2:
	case GL_FLOAT_MAT3x4:
	case GL_FLOAT_MAT4x2:
	case GL_FLOAT_MAT4x3:
		return UNIFORM_MATRIX;
	case GL_BOOL:
	case GL_BOOL_VEC2:
	case GL_BOOL_VEC3:
	case GL_BOOL_VEC4:
		return UNIFORM_BOOL;
	case GL_SAMPLER_1D:
	case GL_SAMPLER_1D_SHADOW:
	case GL_SAMPLER_1D_ARRAY:
	case GL_SAMPLER_1D_ARRAY_SHADOW:
	case GL_SAMPLER_2D:
	case GL_SAMPLER_2D_MULTISAMPLE:
	case GL_SAMPLER_2D_MULTISAMPLE_ARRAY:
	case GL_SAMPLER_2D_RECT:
	case GL_SAMPLER_2D_RECT_SHADOW:
	case GL_SAMPLER_2D_SHADOW:
	case GL_SAMPLER_2D_ARRAY:
	case GL_SAMPLER_2D_ARRAY_SHADOW:
	case GL_SAMPLER_3D:
	case GL_SAMPLER_CUBE:
	case GL_SAMPLER_CUBE_SHADOW:
	case GL_SAMPLER_CUBE_MAP_ARRAY:
	case GL_SAMPLER_CUBE_MAP_ARRAY_SHADOW:
		return UNIFORM_SAMPLER;
	case GL_SAMPLER_BUFFER:
	case GL_INT_SAMPLER_BUFFER:
	case GL_UNSIGNED_INT_SAMPLER_BUFFER:
		return UNIFORM_TEXELBUFFER;
	default:
		return UNIFORM_UNKNOWN;
	}
}

TextureType Shader::getUniformTextureType(GLenum type) const
{
	switch (type)
	{
	case GL_SAMPLER_1D:
	case GL_SAMPLER_1D_SHADOW:
	case GL_SAMPLER_1D_ARRAY:
	case GL_SAMPLER_1D_ARRAY_SHADOW:
		// 1D-typed textures are not supported.
		return TEXTURE_MAX_ENUM;
	case GL_SAMPLER_2D:
	case GL_SAMPLER_2D_SHADOW:
		return TEXTURE_2D;
	case GL_SAMPLER_2D_MULTISAMPLE:
	case GL_SAMPLER_2D_MULTISAMPLE_ARRAY:
		// Multisample textures are not supported.
		return TEXTURE_MAX_ENUM;
	case GL_SAMPLER_2D_RECT:
	case GL_SAMPLER_2D_RECT_SHADOW:
		// Rectangle textures are not supported.
		return TEXTURE_MAX_ENUM;
	case GL_SAMPLER_2D_ARRAY:
	case GL_SAMPLER_2D_ARRAY_SHADOW:
		return TEXTURE_2D_ARRAY;
	case GL_SAMPLER_3D:
		return TEXTURE_VOLUME;
	case GL_SAMPLER_CUBE:
	case GL_SAMPLER_CUBE_SHADOW:
		return TEXTURE_CUBE;
	case GL_SAMPLER_CUBE_MAP_ARRAY:
	case GL_SAMPLER_CUBE_MAP_ARRAY_SHADOW:
		// Cubemap array textures are not supported.
		return TEXTURE_MAX_ENUM;
	default:
		return TEXTURE_MAX_ENUM;
	}
}

DataBaseType Shader::getUniformTexelBufferType(GLenum type) const
{
	switch (type)
	{
	case GL_SAMPLER_BUFFER:
		return DATA_BASETYPE_FLOAT;
	case GL_INT_SAMPLER_BUFFER:
		return DATA_BASETYPE_INT;
	case GL_UNSIGNED_INT_SAMPLER_BUFFER:
		return DATA_BASETYPE_UINT;
	default:
		return DATA_BASETYPE_MAX_ENUM;
	}
}

bool Shader::isDepthTextureType(GLenum type) const
{
	switch (type)
	{
	case GL_SAMPLER_1D_SHADOW:
	case GL_SAMPLER_1D_ARRAY_SHADOW:
	case GL_SAMPLER_2D_SHADOW:
	case GL_SAMPLER_2D_ARRAY_SHADOW:
	case GL_SAMPLER_CUBE_SHADOW:
	case GL_SAMPLER_CUBE_MAP_ARRAY_SHADOW:
		return true;
	default:
		return false;
	}
}

} // opengl
} // graphics
} // love