new example: shaders_texture_drawing

examples/shaders/resources/shaders/glsl330/cubes_panning.fs

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+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec2 fragTexCoord;
+in vec4 fragColor;
+
+// Output fragment color
+out vec4 finalColor;
+
+// Custom variables
+#define PI 3.14159265358979323846
+uniform float uTime = 0.0;
+
+float divisions = 5.0;
+float angle = 0.0;
+
+vec2 VectorRotateTime(vec2 v, float speed)
+{
+    float time = uTime*speed;
+    float localTime = fract(time);  // The time domain this works on is 1 sec.
+    
+    if ((localTime >= 0.0) && (localTime < 0.25)) angle = 0.0;
+    else if ((localTime >= 0.25) && (localTime < 0.50)) angle = PI/4*sin(2*PI*localTime - PI/2);
+    else if ((localTime >= 0.50) && (localTime < 0.75)) angle = PI*0.25;
+    else if ((localTime >= 0.75) && (localTime < 1.00)) angle = PI/4*sin(2*PI*localTime);
+    
+    // Rotate vector by angle
+    v -= 0.5;
+    v =  mat2(cos(angle), -sin(angle), sin(angle), cos(angle))*v;
+    v += 0.5;
+    
+    return v;
+}
+
+float Rectangle(in vec2 st, in float size, in float fill) 
+{
+  float roundSize = 0.5 - size/2.0;
+  float left = step(roundSize, st.x);
+  float top = step(roundSize, st.y);
+  float bottom = step(roundSize, 1.0 - st.y);
+  float right = step(roundSize, 1.0 - st.x);
+
+  return (left*bottom*right*top)*fill;
+}
+
+void main()
+{ 
+    vec2 fragPos = fragTexCoord;
+    fragPos.xy += uTime/9.0;
+
+    fragPos *= divisions;
+    vec2 ipos = floor(fragPos);  // Get the integer coords
+    vec2 fpos = fract(fragPos);  // Get the fractional coords
+
+    fpos = VectorRotateTime(fpos, 0.2);
+    
+    float alpha = Rectangle(fpos, 0.216, 1.0);
+    vec3 color = vec3(0.3, 0.3, 0.3);
+
+    finalColor = vec4(color, alpha);
+}

examples/shaders/shaders_texture_drawing.c

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+/*******************************************************************************************
+*
+*   raylib [textures] example - Shader texture drawing
+*
+*   This example illustrates how to draw on a blank texture using a shader
+*
+*   This example has been created using raylib 2.0 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2019 Michał Ciesielski and Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 800;
+    int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shaders] example - shader texture drawing");
+
+    Image imBlank = GenImageColor(1024, 1024, BLANK);
+    Texture2D texture = LoadTextureFromImage(imBlank);  // Load blank texture to fill on shader
+    UnloadImage(imBlank);
+
+    // NOTE: Using GLSL 330 shader version, on OpenGL ES 2.0 use GLSL 100 shader version
+    Shader shader = LoadShader(0, "resources/shaders/glsl330/cubes_panning.fs");
+
+    float time = 0.0f;
+    int timeLoc = GetShaderLocation(shader, "uTime");
+    SetShaderValue(shader, timeLoc, &time, UNIFORM_FLOAT);
+
+    SetTargetFPS(60);
+    //--------------------------------------------------------------------------------------
+
+    while (!WindowShouldClose())
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        time = GetTime();
+        SetShaderValue(shader, timeLoc, &time, UNIFORM_FLOAT);
+        //----------------------------------------------------------------------------------
+        
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            BeginShaderMode(shader);    // Enable our custom shader for next shapes/textures drawings
+                DrawTexture(texture, 0, 0, WHITE);  // Drawing BLANK texture, all magic happens on shader
+            EndShaderMode();            // Disable our custom shader, return to default shader
+            
+            DrawText("BACKGROUND is PAINTED and ANIMATED on SHADER!", 10, 10, 20, MAROON);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+    
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadShader(shader);
+
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}