Support multiple sample2D on batch drawing #1333

examples/shaders/resources/shaders/glsl100/color_mix.fs

@@ -0,0 +1,21 @@
+#version 100
+
+precision mediump float;
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform sampler2D texture1;
+uniform vec4 colDiffuse;
+
+void main()
+{
+    // Texel color fetching from texture sampler
+    vec4 texelColor0 = texture2D(texture0, fragTexCoord);
+    vec4 texelColor1 = texture2D(texture1, fragTexCoord);
+
+    gl_FragColor = (texelColor0 + texelColor1)*0.5f;
+}

examples/shaders/resources/shaders/glsl330/color_mix.fs

@@ -0,0 +1,22 @@
+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec3 vertexPos;
+in vec2 fragTexCoord;
+in vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform sampler2D texture1;
+uniform vec4 colDiffuse;
+
+out vec4 finalColor;
+
+void main()
+{
+    // Texel color fetching from texture sampler
+    vec4 texelColor0 = texture(texture0, fragTexCoord);
+    vec4 texelColor1 = texture(texture1, fragTexCoord);
+
+    finalColor = (texelColor0 + texelColor1)*0.5f;
+}

examples/shaders/shaders_multi_sample2d.c

@@ -0,0 +1,89 @@
+/*******************************************************************************************
+*
+*   raylib [shaders] example - Multiple sample2D with default batch system
+*
+*   NOTE: This example requires raylib OpenGL 3.3 or ES2 versions for shaders support,
+*         OpenGL 1.1 does not support shaders, recompile raylib to OpenGL 3.3 version.
+*
+*   NOTE: Shaders used in this example are #version 330 (OpenGL 3.3), to test this example
+*         on OpenGL ES 2.0 platforms (Android, Raspberry Pi, HTML5), use #version 100 shaders
+*         raylib comes with shaders ready for both versions, check raylib/shaders install folder
+*
+*   This example has been created using raylib 3.5 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2020 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#if defined(PLATFORM_DESKTOP)
+    #define GLSL_VERSION            330
+#else   // PLATFORM_RPI, PLATFORM_ANDROID, PLATFORM_WEB
+    #define GLSL_VERSION            100
+#endif
+
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib - multiple sample2D");
+
+    Image imRed = GenImageColor(800, 450, (Color){ 255, 0, 0, 255 });
+    Texture texRed = LoadTextureFromImage(imRed);
+    UnloadImage(imRed);
+
+    Image imBlue = GenImageColor(800, 450, (Color){ 0, 0, 255, 255 });
+    Texture texBlue = LoadTextureFromImage(imBlue);
+    UnloadImage(imBlue);
+
+    Shader shader = LoadShader(0, TextFormat("resources/shaders/glsl%i/color_mix.fs", GLSL_VERSION));
+    
+    // Set an additional sampler2D, using another texture1
+    // NOTE: Additional samplers are enabled for all batch calls
+    SetShaderValueTexture(shader, GetShaderLocation(shader, "texture1"), texBlue);
+
+    SetTargetFPS(60);                           // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())                // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        // ...
+        //----------------------------------------------------------------------------------
+        
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+        
+            ClearBackground(RAYWHITE);
+
+            BeginShaderMode(shader);
+            
+                // We are drawing texture using default sampler2D but
+                // but additional texture units will be also enabled
+                DrawTexture(texRed, 0, 0, WHITE);
+                
+            EndShaderMode();
+            
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadShader(shader);       // Unload shader
+    UnloadTexture(texRed);      // Unload texture
+    UnloadTexture(texBlue);     // Unload texture
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}

src/rlgl.h

@@ -3356,12 +3356,14 @@ void SetShaderValueTexture(Shader shader, int uniformLoc, Texture2D texture)
     glUseProgram(shader.id);
 
     // Register a new active texture for the internal batch system
+    // NOTE: Default texture is always activated as GL_TEXTURE0
     for (int i = 0; i < 4; i++) 
     {
-        if (RLGL.State.activeTextureId[i] == 0) 
+        if (RLGL.State.activeTextureId[i] == 0)
         {
-            glUniform1i(uniformLoc, i + 1); // Activate new texture unit (0 is used by default texture)
+            glUniform1i(uniformLoc, 1 + i);             // Activate new texture unit
             RLGL.State.activeTextureId[i] = texture.id; // Save texture id for binding on drawing
+            break;
         }
     }
 
@@ -4461,9 +4463,10 @@ static void DrawRenderBatch(RenderBatch *batch)
                 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, batch->vertexBuffer[batch->currentBuffer].vboId[3]);
             }
 
-            glActiveTexture(GL_TEXTURE0);   // One texture is always active for default shader
-            glUniform1i(RLGL.State.currentShader.locs[LOC_MAP_DIFFUSE], 0); // Active texture 0
-
+            // Setup some default shader values
+            glUniform4f(RLGL.State.currentShader.locs[LOC_COLOR_DIFFUSE], 1.0f, 1.0f, 1.0f, 1.0f);
+            glUniform1i(RLGL.State.currentShader.locs[LOC_MAP_DIFFUSE], 0);  // Active default sampler2D: texture0
+            
             // Activate additional sampler textures
             // Those additional textures will be common for all draw calls of the batch
             for (int i = 0; i < 4; i++)
@@ -4474,13 +4477,15 @@ static void DrawRenderBatch(RenderBatch *batch)
                     glBindTexture(GL_TEXTURE_2D, RLGL.State.activeTextureId[i]);
                 }
             }
-            
-            // Setup some default shader values
-            glUniform4f(RLGL.State.currentShader.locs[LOC_COLOR_DIFFUSE], 1.0f, 1.0f, 1.0f, 1.0f);
+
+            // Activate default sampler texture (one texture is always active for default shader)
+            // NOTE: Batch system accumulates calls by texture0 changes,
+            // additional textures are enabled for all the draw calls
+            glActiveTexture(GL_TEXTURE0);
 
             for (int i = 0, vertexOffset = 0; i < batch->drawsCounter; i++)
             {
-                // Texture 0 is always active by default, bind the texture for current draw call
+                // Texture0 is always active by default, bind the texture for current draw call
                 glBindTexture(GL_TEXTURE_2D, batch->draws[i].textureId);
 
                 if ((batch->draws[i].mode == RL_LINES) || (batch->draws[i].mode == RL_TRIANGLES)) glDrawArrays(batch->draws[i].mode, vertexOffset, batch->draws[i].vertexCount);