REVIEWED: raylib_opengl_interop

examples/others/opengl_interop.c → examples/others/raylib_opengl_interop.c

@@ -2,7 +2,7 @@
 *
 *   raylib [shaders] example - OpenGL point particle system
 *
-*   This example has been created using raylib 2ad3eb1 (www.raylib.com)
+*   This example has been created using raylib 3.8 (www.raylib.com)
 *   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
 *
 *   Example contributed by Stephan Soller (@arkanis -  http://arkanis.de/)
@@ -24,8 +24,9 @@
 ********************************************************************************************/
 
 #include "raylib.h"
-#include "rlgl.h"
-#include "glad.h"
+#include "rlgl.h"           // Required for: rlDrawRenderBatchActive(), rlGetMatrixModelview(), rlGetMatrixProjection()
+#include "glad.h"           // Required for: OpenGL functionality 
+#include "raymath.h"        // Required for: MatrixMultiply(), MatrixToFloat()
 
 #if defined(PLATFORM_DESKTOP)
     #define GLSL_VERSION            330
@@ -33,6 +34,15 @@
     #define GLSL_VERSION            100
 #endif
 
+#define MAX_PARTICLES       1000
+
+// Particle type
+typedef struct Particle {
+    float x;
+    float y;
+    float period;
+} Particle;
+
 int main()
 {
     // Initialization
@@ -42,32 +52,34 @@ int main()
 
     InitWindow(screenWidth, screenHeight, "raylib - point particles");
 
-    Shader shader = LoadShader(
-        TextFormat("resources/shaders/glsl%i/point_particle.vs", GLSL_VERSION),
-        TextFormat("resources/shaders/glsl%i/point_particle.fs", GLSL_VERSION));
+    Shader shader = LoadShader(TextFormat("resources/shaders/glsl%i/point_particle.vs", GLSL_VERSION),
+                               TextFormat("resources/shaders/glsl%i/point_particle.fs", GLSL_VERSION));
+
     int currentTimeLoc = GetShaderLocation(shader, "currentTime");
     int colorLoc = GetShaderLocation(shader, "color");
 
     // Initialize the vertex buffer for the particles and assign each particle random values
-    struct { float x, y, period; } particles[10000];
-    const size_t particleCount = sizeof(particles) / sizeof(particles[0]);
-    for (size_t i = 0; i < particleCount; i++)
+    Particle particles[MAX_PARTICLES] = { 0 };
+
+    for (int i = 0; i < MAX_PARTICLES; i++)
     {
-        particles[i].x = GetRandomValue(20, screenWidth - 20);
-        particles[i].y = GetRandomValue(50, screenHeight - 20);
-        // Give each particle a slightly different period. But don't spread it to much. This way the particles line up
-        // every so often and you get a glimps of what is going on.
-        particles[i].period = GetRandomValue(10, 30) / 10.0f;
+        particles[i].x = (float)GetRandomValue(20, screenWidth - 20);
+        particles[i].y = (float)GetRandomValue(50, screenHeight - 20);
+        
+        // Give each particle a slightly different period. But don't spread it to much. 
+        // This way the particles line up every so often and you get a glimps of what is going on.
+        particles[i].period = (float)GetRandomValue(10, 30)/10.0f;
     }
 
-    // Create a plain OpenGL vertex buffer with the data and an vertex array object that feeds the data from the buffer
-    // into the vertexPosition shader attribute.
-    GLuint vao = 0, vbo = 0;
+    // Create a plain OpenGL vertex buffer with the data and an vertex array object 
+    // that feeds the data from the buffer into the vertexPosition shader attribute.
+    GLuint vao = 0;
+    GLuint vbo = 0;
     glGenVertexArrays(1, &vao);
     glBindVertexArray(vao);
         glGenBuffers(1, &vbo);
         glBindBuffer(GL_ARRAY_BUFFER, vbo);
-        glBufferData(GL_ARRAY_BUFFER, sizeof(particles), particles, GL_STATIC_DRAW);
+        glBufferData(GL_ARRAY_BUFFER, MAX_PARTICLES*sizeof(Particle), particles, GL_STATIC_DRAW);
         // Note: LoadShader() automatically fetches the attribute index of "vertexPosition" and saves it in shader.locs[SHADER_LOC_VERTEX_POSITION]
         glVertexAttribPointer(shader.locs[SHADER_LOC_VERTEX_POSITION], 3, GL_FLOAT, GL_FALSE, 0, 0);
         glEnableVertexAttribArray(0);
@@ -89,32 +101,33 @@ int main()
             ClearBackground(WHITE);
 
             DrawRectangle(10, 10, 210, 30, MAROON);
-            DrawText(TextFormat("%zu particles in one vertex buffer", particleCount), 20, 20, 10, RAYWHITE);
+            DrawText(TextFormat("%zu particles in one vertex buffer", MAX_PARTICLES), 20, 20, 10, RAYWHITE);
+            
+            rlDrawRenderBatchActive();      // Draw iternal buffers data (previous draw calls)
 
             // Switch to plain OpenGL
             //------------------------------------------------------------------------------
-            // rlglDraw() in raylib 3.5
-            rlDrawRenderBatchActive();
             glUseProgram(shader.id);
+            
                 glUniform1f(currentTimeLoc, GetTime());
 
                 Vector4 color = ColorNormalize((Color){ 255, 0, 0, 128 });
-                glUniform4fv(colorLoc, 1, (float*)&color);
+                glUniform4fv(colorLoc, 1, (float *)&color);
 
-                // The the current model view projection matrix so the particle system is displayed and transformed
-                // (e.g. by cameras) just like everything else.
-                // GetMatrixModelview() and GetMatrixProjection() in raylib 3.5
+                // Get the current modelview and projection matrix so the particle system is displayed and transformed
                 Matrix modelViewProjection = MatrixMultiply(rlGetMatrixModelview(), rlGetMatrixProjection());
+                
                 glUniformMatrix4fv(shader.locs[SHADER_LOC_MATRIX_MVP], 1, false, MatrixToFloat(modelViewProjection));
 
                 glBindVertexArray(vao);
-                    glDrawArrays(GL_POINTS, 0, particleCount);
+                    glDrawArrays(GL_POINTS, 0, MAX_PARTICLES);
                 glBindVertexArray(0);
+                
             glUseProgram(0);
-
-            // And back to raylib again
             //------------------------------------------------------------------------------
+            
             DrawFPS(screenWidth - 100, 10);
+            
         EndDrawing();
         //----------------------------------------------------------------------------------
     }
@@ -124,8 +137,9 @@ int main()
     glDeleteBuffers(1, &vbo);
     glDeleteVertexArrays(1, &vao);
 
-    UnloadShader(shader);
-    CloseWindow();        // Close window and OpenGL context
+    UnloadShader(shader);   // Unload shader
+
+    CloseWindow();          // Close window and OpenGL context
     //--------------------------------------------------------------------------------------
 
     return 0;