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#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <emscripten.h>
#include <emscripten/html5.h>
#include <GLES2/gl2.h>
#include <EGL/egl.h>
#include "mathlib.h"
#include "Shader.h"
// Shader code inlined
const char* orthographicVertex =
"attribute vec2 position; \n"
"attribute vec4 color; \n"
"uniform mat4 projection; \n"
"uniform mat4 model; \n"
"varying lowp vec4 VertexColor; \n"
"void main() { \n"
" vec4 fragmentPosition = projection * model * vec4(position, 1, 1); \n"
" gl_Position = fragmentPosition; \n"
" VertexColor = color; \n"
"}";
const char* orthographicFragment =
"varying lowp vec4 VertexColor; \n"
"void main() { \n"
" gl_FragColor = VertexColor; \n"
"}";
struct OrthographicProgramData {
GLuint shader;
struct {
int position;
int color;
} attributes;
struct {
int projection;
int model;
} uniformVariables;
};
struct OrthographicVertex {
Vector2 position;
Vector4 color;
};
// Create a triangle
struct TriangleObject {
OrthographicVertex vertices[3];
GLuint mVao;
GLuint mVbo;
Mat4x4 model;
void initialize(OrthographicProgramData* programData) {
useShader(programData->shader);
glGenVertexArrays(1, &mVao);
glBindVertexArray(mVao);
glGenBuffers(1, &mVbo);
glBindBuffer(GL_ARRAY_BUFFER, mVbo);
glBufferData(GL_ARRAY_BUFFER, 3 * sizeof(OrthographicVertex), &vertices[0], GL_STATIC_DRAW);
for (int idx = 0; idx < 3; idx++) {
printf("%f, %f\n", vertices[idx].position.x, vertices[idx].position.y);
}
glEnableVertexAttribArray(programData->attributes.position);
glVertexAttribPointer(programData->attributes.position, 2, GL_FLOAT, GL_FALSE, sizeof(OrthographicVertex), (GLvoid *)0);
glEnableVertexAttribArray(programData->attributes.color);
glVertexAttribPointer(programData->attributes.color, 4, GL_FLOAT, GL_FALSE, sizeof(OrthographicVertex), (GLvoid *)offsetof(OrthographicVertex, color));
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
void render(OrthographicProgramData* programData) {
setShaderMat4(programData->uniformVariables.model, model);
glBindVertexArray(mVao);
glDrawArrays(GL_TRIANGLES, 0, 3);
glBindVertexArray(0);
}
};
int main() {
printf("Initializing the canvas...\n");
emscripten_set_canvas_element_size( "#wasm_canvas", 640, 480 );
EmscriptenWebGLContextAttributes attrs;
emscripten_webgl_init_context_attributes(&attrs);
attrs.enableExtensionsByDefault = 1;
attrs.majorVersion = 3;
attrs.minorVersion = 0;
EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context( "#wasm_canvas", &attrs );
if (!context)
{
attrs.majorVersion = 1;
context = emscripten_webgl_create_context( "#wasm_canvas", &attrs );
if (context) printf("Skipping test: WebGL 2.0 is not available.\n");
else printf("Test failed: WebGL is not available!\n");
return 0;
}
emscripten_webgl_make_context_current(context);
printf("Canvas ready.\n");
printf("Compiling shaders...\n");
GLuint shader = loadShader(orthographicVertex, orthographicFragment);
useShader(shader);
OrthographicProgramData programData;
programData.shader = shader;
programData.attributes.position = getShaderAttribute(shader, "position");
programData.attributes.color = getShaderAttribute(shader, "color");
programData.uniformVariables.projection = getShaderUniform(shader, "projection");
programData.uniformVariables.model = getShaderUniform(shader, "model");
printf("Compiling ready.\n");
TriangleObject triangle;
triangle.vertices[0] = { Vector2 { 50, 50 }, Vector4 { 1.f, 0.f, 0.f, 1.f }};
triangle.vertices[1] = { Vector2 { 150, 300 }, Vector4 { 0.f, 1.f, 0.f, 1.f }};
triangle.vertices[2] = { Vector2 { 250, 50 }, Vector4 { 0.f, 0.f, 1.f, 1.f }};
triangle.initialize(&programData);
Mat4x4 projection = Mat4x4().getOrthographicMatrix(0, 480, 0, 640);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glDepthMask(GL_TRUE);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClearDepth(1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
useShader(shader);
setShaderMat4(programData.uniformVariables.projection, projection);
triangle.render(&programData);
return EXIT_SUCCESS;
}
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