feat: moving DVD-like box

main.cpp

@@ -15,8 +15,8 @@
 #define SCREEN_WIDTH 1600
 #define SCREEN_HEIGHT 720
 
-#define BOX_WIDTH 250
+#define BOX_WIDTH 100
-#define BOX_HEIGHT 250
+#define BOX_HEIGHT 100
 
 static SDL_Window *window = NULL;
 
@@ -25,45 +25,26 @@ static bool running = true;
 static Uint8 color = 0x18;
 
 static Uint64 elapsed = 0;
-static float boxX = 0.f;
+static float boxVelX = 0.5f;
-static float boxY = 0.f;
+static float boxVelY = 0.5f;
-static float boxVelX = 1.f;
-static float boxVelY = 1.f;
 
-static float boxSpeed = 250.f;
+static float boxSpeed = 300.f;
 
 const char* vShader = "#version 300 es\n"
 "layout (location = 0) in vec2 aPos;\n"
-"uniform mat4 uTransform;\n"
-"uniform vec4 uColor;\n"
-"out vec4 color;\n"
 "void main()\n"
 "{\n"
-"    gl_Position = uTransform * vec4(aPos, 0.0, 1.0);\n"
+"    gl_Position = vec4(aPos, 0.0, 1.0);\n"
-"    color = uColor;\n"
 "}";
 
 const char* fShader = "#version 300 es\n"
 "precision mediump float;\n"
 "out vec4 fragColor;\n"
-"in vec4 color;\n"
 "void main()\n"
 "{\n"
-"    fragColor = color;\n"
+"    fragColor = vec4(0.8, 0.8, 0.8, 1.0);\n"
 "}";
 
-void makeRotationZ(float angle, float* m)
-{
-    float c = cosf(angle);
-    float s = sinf(angle);
-
-    // column-major (OpenGL style)
-    m[0] =  c; m[4] = -s; m[8]  = 0; m[12] = 0;
-    m[1] =  s; m[5] =  c; m[9]  = 0; m[13] = 0;
-    m[2] =  0; m[6] =  0; m[10] = 1; m[14] = 0;
-    m[3] =  0; m[7] =  0; m[11] = 0; m[15] = 1;
-}
-
 void computeLetterbox(int windowW, int windowH,
                       int logicalW, int logicalH,
                       int* x, int* y, int* w, int* h)
@@ -80,6 +61,13 @@ void computeLetterbox(int windowW, int windowH,
     *y = (windowH - *h) / 2;
 }
 
+struct Rect {
+	float x;
+	float y;
+	float w;
+	float h;
+};
+
 extern "C" int APP_MAIN(int argc, char **argv) {
     SDL_SetAppMetadata("Example Renderer Primitives", "1.0", "com.example.renderer-primitives");
     SDL_SetHint(SDL_HINT_ORIENTATIONS, "LandscapeLeft LandscapeRight");
@@ -141,15 +129,14 @@ extern "C" int APP_MAIN(int argc, char **argv) {
     glDeleteShader(vertexShader);
     glDeleteShader(fragmentShader);
 
-    float vertices[] = {
+    float vertices[12] = {0};
-        // positions (x, y)
-        -0.5f, -0.5f,
-        0.5f, -0.5f,
-        0.5f, 0.5f,
 	
-        -0.5f, -0.5f,
+		Rect rect = {
-        0.5f, 0.5f,
+			.x = 50.f,
-        -0.5f, 0.5f};
+			.y = 50.f,
+			.w = BOX_WIDTH,
+			.h = BOX_HEIGHT,
+		};
 
     GLuint vao, vbo;
     glGenVertexArrays(1, &vao);
@@ -157,7 +144,7 @@ extern "C" int APP_MAIN(int argc, char **argv) {
 
     glBindVertexArray(vao);
     glBindBuffer(GL_ARRAY_BUFFER, vbo);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_DYNAMIC_DRAW);
 
     glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void *)0);
     glEnableVertexAttribArray(0);
@@ -168,21 +155,18 @@ extern "C" int APP_MAIN(int argc, char **argv) {
     int drawableW, drawableH;
     SDL_GetWindowSizeInPixels(window, &drawableW, &drawableH);
 
+#if defined(__ANDROID__)
     int vx, vy, vw, vh;
     computeLetterbox(drawableW, drawableH,
                      SCREEN_WIDTH, SCREEN_HEIGHT,
                      &vx, &vy, &vw, &vh);
 
     glViewport(vx, vy, vw, vh);
+#else
+    glViewport(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
+#endif
     glEnable(GL_DEPTH_TEST);
 
-    float transform[16];
-    float color[4];
-    color[0] = 0x18 / 255.f;
-    color[1] = 0xFF / 255.f;
-    color[2] = 0x18 / 255.f;
-    color[3] = 0xFF / 255.f;
-
     while (running) {
         SDL_Event event;
         while (SDL_PollEvent(&event)) {
@@ -197,31 +181,46 @@ extern "C" int APP_MAIN(int argc, char **argv) {
         // SDL_Log("dt: %f\n", dt);
         dt /= 1000.f;
 
-        boxX += boxSpeed * boxVelX * dt;
+        rect.x += boxSpeed * boxVelX * dt;
-        boxY += boxSpeed * boxVelY * dt;
+        rect.y += boxSpeed * boxVelY * dt;
-        boxSpeed += 50.f * dt;
+        // boxSpeed += 50.f * dt;
 
-        if (boxX + BOX_WIDTH >= SCREEN_WIDTH || boxX <= 0) boxVelX *= -1.f;
+        if (rect.x + BOX_WIDTH >= SCREEN_WIDTH || rect.x <= 0) boxVelX *= -1.f;
-        if (boxY + BOX_HEIGHT >= SCREEN_HEIGHT || boxY <= 0) boxVelY *= -1.f;
+        if (rect.y + BOX_HEIGHT >= SCREEN_HEIGHT || rect.y <= 0) boxVelY *= -1.f;
+
+				// float xProj = -1 + rect.x / ((float)SCREEN_WIDTH / 2);
+				// float yProj = rect.y / ((float)SCREEN_HEIGHT / 2);
+
+				float xProj = (rect.x / SCREEN_WIDTH) * 2.0f - 1.0f;
+				float yProj = 1.0f - (rect.y / SCREEN_HEIGHT) * 2.0f;
+
+				float wProj = (rect.w / SCREEN_WIDTH) * 2.0f;
+				float hProj = (rect.h / SCREEN_HEIGHT) * 2.0f;
+				SDL_Log("%f::%f (%f:%f)\n", xProj, yProj, wProj, hProj);
+
+				vertices[0] = xProj;
+				vertices[1] = yProj;
+				vertices[2] = xProj + wProj;
+				vertices[3] = yProj;
+				vertices[4] = xProj + wProj;
+				vertices[5] = yProj - hProj;
+
+				vertices[6] = xProj;
+				vertices[7] = yProj;
+				vertices[8] = xProj;
+				vertices[9] = yProj - hProj;
+				vertices[10] = xProj + wProj;
+				vertices[11] = yProj - hProj;
 
         glClearColor(0x18/255.f, 0x18/255.f, 0x18/255.f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
         // Draw your 3D stuff here
-
+				glBindVertexArray(vao);
-        float angle = SDL_GetTicks() / 1000.0f; // rotates over time
+				glBindBuffer(GL_ARRAY_BUFFER, vbo);
-
+				glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_DYNAMIC_DRAW);
-        makeRotationZ(angle, transform);
-
-        GLuint tranformLoc = glGetUniformLocation(program, "uTransform");
-        GLuint colorLoc = glGetUniformLocation(program, "uColor");
 
         glUseProgram(program);
-        glUniformMatrix4fv(tranformLoc, 1, GL_FALSE, transform);
-
-        color[1] = (float)((int)angle * 10 % 255) / 255.f;
-        glUniform4fv(colorLoc, 1, color);
-
         glBindVertexArray(vao);
 
         glDrawArrays(GL_TRIANGLES, 0, 6);