JosephFerano/terrain-opengl
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Draw a simple quad for now to make sure things are working

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This commit is contained in:
Joseph Ferano 2023-10-31 14:18:36 +07:00
parent b6110e3c73
commit e1878bc565
3 changed files with 82 additions and 37 deletions
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114
main.c
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@ -54,39 +54,66 @@ int main(void) {
SDL_GL_SetSwapInterval(1); SDL_GL_SetSwapInterval(1);
int w, h, c; // int w, h, c;
unsigned char *terrain_img = stbi_load("terrain.png", &w, &h, &c, 0); // unsigned char *terrain_img = stbi_load("terrain.png", &w, &h, &c, 0);
int w = 20;
int h = 20;
int vcount = w * h * 3; int vcount = w * h * 3;
float *verts = malloc(vcount * sizeof(float)); float *verts = malloc(vcount * sizeof(float));
float scale_y = 1.0f; // float scale_y = 1.0f;
float shift_y = 16.0f; // float shift_y = 16.0f;
for (int row = 0; row < h; row++) { // for (int row = 0; row < h; row++) {
for (int col = 0; col < w; col++) { // for (int col = 0; col < w; col++) {
unsigned char *texel = terrain_img + (row * w + col) * c; // unsigned char *texel = terrain_img + (row * w + col) * c;
unsigned char y = texel[0]; // unsigned char y = texel[0];
// float *v = &verts[(row * w + col) * 3];
// *(v+0) = -w/2 + col;
// *(v+1) = y * scale_y + shift_y;
// *(v+2) = -h/2 + row;
// }
// }
// for (int row = 0; row < h; row++) {
// for (int col = 0; col < w; col++) {
// float *v = &verts[(row * w + col) * 3];
// *(v+0) = -w/2 + col;
// *(v+1) = 0.0f;
// *(v+2) = -h/2 + row;
// }
// }
float quadVerts[] = {
// Position
0.5f, 0.5f, 0.0f,
0.5f, -0.5f, 0.0f,
-0.5f, -0.5f, 0.0f,
-0.5f, 0.5f, 0.0f,
};
unsigned int quadIndices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
float *v = &verts[(row * w + col) * 3];
*(v+0) = -w/2 + col;
*(v+1) = y * scale_y + shift_y;
*(v+2) = -h/2 + row;
}
}
printf("Loaded %d vertices\n", w * h); printf("Loaded %d vertices\n", w * h);
stbi_image_free(terrain_img); // stbi_image_free(terrain_img);
unsigned int icount = w * (h - 1) * 2; // unsigned int icount = w * (h - 1) * 2;
unsigned int *indices = malloc(icount * sizeof(unsigned int)); // unsigned int *indices = malloc(icount * sizeof(unsigned int));
for (int row = 0; row < h - 1; row++) { // for (int row = 0; row < h - 1; row++) {
for (int col = 0; col < w; col++) { // for (int col = 0; col < w; col++) {
unsigned int idx1 = w * (row + 0) + col; // unsigned int idx1 = w * (row + 0) + col;
unsigned int idx2 = w * (row + 1) + col; // unsigned int idx2 = w * (row + 1) + col;
*(indices + idx1) = idx1; // *(indices + idx1) = idx1;
*(indices + idx2) = idx2; // *(indices + idx2) = idx2;
} // }
} // }
const unsigned int NUM_STRIPS = h - 1; // const unsigned int NUM_STRIPS = h - 1;
const unsigned int NUM_VERTS_PER_STRIP = w * 2; // const unsigned int NUM_VERTS_PER_STRIP = w * 2;
unsigned int terrainVAO, terrainVBO, terrainIBO; unsigned int terrainVAO, terrainVBO, terrainIBO;
glGenVertexArrays(1, &terrainVAO); glGenVertexArrays(1, &terrainVAO);
@ -94,7 +121,8 @@ int main(void) {
glGenBuffers(1, &terrainVBO); glGenBuffers(1, &terrainVBO);
glBindBuffer(GL_ARRAY_BUFFER, terrainVBO); glBindBuffer(GL_ARRAY_BUFFER, terrainVBO);
glBufferData(GL_ARRAY_BUFFER, vcount * sizeof(float), verts, GL_STATIC_DRAW); // glBufferData(GL_ARRAY_BUFFER, vcount * sizeof(float), verts, GL_STATIC_DRAW);
glBufferData(GL_ARRAY_BUFFER, sizeof(quadVerts), quadVerts, GL_STATIC_DRAW);
// position attribute // position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
@ -102,7 +130,7 @@ int main(void) {
glGenBuffers(1, &terrainIBO); glGenBuffers(1, &terrainIBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, terrainIBO); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, terrainIBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, icount * sizeof(unsigned), indices, GL_STATIC_DRAW); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(quadIndices), quadIndices, GL_STATIC_DRAW);
// Disable depth test and face culling. // Disable depth test and face culling.
glDisable(GL_DEPTH_TEST); glDisable(GL_DEPTH_TEST);
glDisable(GL_CULL_FACE); glDisable(GL_CULL_FACE);
@ -118,22 +146,30 @@ int main(void) {
glm_mat4_identity(projection); glm_mat4_identity(projection);
float aspectRatio = (float)SCREEN_WIDTH / (float)SCREEN_HEIGHT; float aspectRatio = (float)SCREEN_WIDTH / (float)SCREEN_HEIGHT;
glm_perspective(45.0f, aspectRatio, 0.1f, 100.0f, projection); glm_perspective(30.0f, aspectRatio, 1.0f, 1000.0f, projection);
glUseProgram(shaderProgram); glUseProgram(shaderProgram);
SDL_Event e; SDL_Event e;
bool quit = false; bool quit = false;
Uint64 now = SDL_GetPerformanceCounter(); Uint64 now = SDL_GetPerformanceCounter();
Uint64 last = 0; Uint64 last = 0;
double dt = 0; double dt = 0;
bool draw_wireframe = false;
float x = 0.0f, y = 0.0f; float x = 0.0f, y = 0.0f;
while (quit == false) { while (quit == false) {
last = now; last = now;
now = SDL_GetPerformanceCounter(); now = SDL_GetPerformanceCounter();
dt = (double)((now - last)*1000 / (double)SDL_GetPerformanceFrequency()); dt = (double)((now - last)*1000 / (double)SDL_GetPerformanceFrequency());
(void)dt;
while (SDL_PollEvent( &e)) { while (SDL_PollEvent( &e)) {
if (e.type == SDL_QUIT) { if (e.type == SDL_QUIT) {
quit = true; quit = true;
} else if (e.type == SDL_KEYDOWN) {
char key = e.key.keysym.sym;
if (key == '1') {
draw_wireframe = !draw_wireframe;
}
} else { } else {
char key = e.key.keysym.sym; char key = e.key.keysym.sym;
float speed = 1.1f; float speed = 1.1f;
if (key == 'w') { if (key == 'w') {
@ -169,12 +205,20 @@ int main(void) {
glViewport(0, 0, screen_width, screen_height); glViewport(0, 0, screen_width, screen_height);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
for (unsigned strip = 0; strip < NUM_STRIPS; strip++) { // for (unsigned strip = 0; strip < NUM_STRIPS; strip++) {
glDrawElements(GL_TRIANGLE_STRIP, // primitive type // glDrawElements(GL_TRIANGLE_STRIP, // primitive type
NUM_VERTS_PER_STRIP, // number of indices to render // NUM_VERTS_PER_STRIP, // number of indices to render
GL_UNSIGNED_INT, // index data type // GL_UNSIGNED_INT, // index data type
(void*)(sizeof(unsigned) * (NUM_VERTS_PER_STRIP+2) * strip)); // offset to starting index // (void*)(sizeof(unsigned) * (NUM_VERTS_PER_STRIP) * strip)); // offset to starting index
// }
if (draw_wireframe) {
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
} else {
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
} }
glBindVertexArray(terrainVAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
SDL_GL_SwapWindow(window); SDL_GL_SwapWindow(window);
} }

3
shaders/main.frag
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@ -4,5 +4,6 @@ out vec4 FragColor;
void main() { void main() {
float h = (Height + 16)/32.0f; // shift and scale the height into a grayscale value float h = (Height + 16)/32.0f; // shift and scale the height into a grayscale value
FragColor = vec4(h, h, h, 1.0); // FragColor = vec4(h, h, h, 1.0);
FragColor = vec4(1, 1, 1, 1.0);
} }

2
shaders/main.vert
View File

@ -7,5 +7,5 @@ uniform mat4 projection;
void main() { void main() {
Height = pos.y; Height = pos.y;
gl_Position = projection * view * model * vec4(pos, 1.0); gl_Position = vec4(pos, 1.0);
} }