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OpenGL example now use the fixed function-pipeline. Code down by 120 lines.

pull/13/merge v1.03
ocornut 10 years ago
parent
ddc7f8b0b0
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cb3d503941
1 changed files with 40 additions and 171 deletions
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  1. 183
      examples/opengl_example/main.cpp

183
examples/opengl_example/main.cpp
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@ -9,80 +9,56 @@
#endif
static GLFWwindow* window;
static GLuint vbo;
static GLuint vao;
static GLuint vertexShader;
static GLuint fragmentShader;
static GLuint shaderProgram;
static GLuint fontTex;
// This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structuer)
// We are using the fixed pipeline.
// A faster way would be to collate all vertices from all cmd_lists into a single vertex buffer
static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
{
size_t total_vtx_count = 0;
for (int n = 0; n < cmd_lists_count; n++)
total_vtx_count += cmd_lists[n]->vtx_buffer.size();
if (total_vtx_count == 0)
return;
// Copy all vertices into a single contiguous GL buffer
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBindVertexArray(vao);
glBufferData(GL_ARRAY_BUFFER, total_vtx_count * sizeof(ImDrawVert), NULL, GL_STREAM_DRAW);
unsigned char* buffer_data = (unsigned char*)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
if (!buffer_data)
if (cmd_lists_count == 0)
return;
for (int n = 0; n < cmd_lists_count; n++)
{
const ImDrawList* cmd_list = cmd_lists[n];
memcpy(buffer_data, &cmd_list->vtx_buffer[0], cmd_list->vtx_buffer.size() * sizeof(ImDrawVert));
buffer_data += cmd_list->vtx_buffer.size() * sizeof(ImDrawVert);
}
glUnmapBuffer(GL_ARRAY_BUFFER);
// Setup render state: alpha-blending enabled, no face culling, no depth testing
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
//glEnable(GL_SCISSOR_TEST);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
// Bind texture and enable our shader
// Bind texture
glBindTexture(GL_TEXTURE_2D, fontTex);
glUseProgram(shaderProgram);
const GLint uniMVP = glGetUniformLocation(shaderProgram, "MVP");
const GLint uniClipRect = glGetUniformLocation(shaderProgram, "ClipRect");
// Setup orthographic projection matrix
const float width = ImGui::GetIO().DisplaySize.x;
const float height = ImGui::GetIO().DisplaySize.y;
const float mvp[4][4] =
{
{ 2.0f/width, 0.0f, 0.0f, 0.0f },
{ 0.0f, 2.0f/-height, 0.0f, 0.0f },
{ 0.0f, 0.0f, -1.0f, 0.0f },
{ -1.0f, 1.0f, 0.0f, 1.0f },
};
glUniformMatrix4fv(uniMVP, 1, GL_FALSE, &mvp[0][0]);
glEnable(GL_TEXTURE_2D);
// Setup matrices
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f, ImGui::GetIO().DisplaySize.x, ImGui::GetIO().DisplaySize.y, 0.0f, -1.0f, +1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Render command lists
int vtx_offset = 0;
for (int n = 0; n < cmd_lists_count; n++)
{
const ImDrawList* cmd_list = cmd_lists[n];
const unsigned char* vtx_buffer = (const unsigned char*)cmd_list->vtx_buffer.begin();
glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer));
glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer+8));
glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (void*)(vtx_buffer+16));
int vtx_offset = 0;
const ImDrawCmd* pcmd_end = cmd_list->commands.end();
for (const ImDrawCmd* pcmd = cmd_list->commands.begin(); pcmd != pcmd_end; pcmd++)
{
glUniform4fv(uniClipRect, 1, (float*)&pcmd->clip_rect);
glScissor((int)pcmd->clip_rect.x, (int)pcmd->clip_rect.y, (int)(pcmd->clip_rect.z - pcmd->clip_rect.x), (int)(pcmd->clip_rect.w - pcmd->clip_rect.y));
glDrawArrays(GL_TRIANGLES, vtx_offset, pcmd->vtx_count);
vtx_offset += pcmd->vtx_count;
}
}
// Cleanup GL state
glBindTexture(GL_TEXTURE_2D, 0);
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glUseProgram(0);
glDisable(GL_SCISSOR_TEST);
}
static const char* ImImpl_GetClipboardTextFn()
@ -103,38 +79,6 @@ static void ImImpl_SetClipboardTextFn(const char* text, const char* text_end)
free(buf);
}
// Shader sources
const GLchar* vertexSource =
"#version 150 core\n"
"uniform mat4 MVP;"
"in vec2 i_pos;"
"in vec2 i_uv;"
"in vec4 i_col;"
"out vec4 col;"
"out vec2 pixel_pos;"
"out vec2 uv;"
"void main() {"
" col = i_col;"
" pixel_pos = i_pos;"
" uv = i_uv;"
" gl_Position = MVP * vec4(i_pos.x, i_pos.y, 0.0f, 1.0f);"
"}";
const GLchar* fragmentSource =
"#version 150 core\n"
"uniform sampler2D Tex;"
"uniform vec4 ClipRect;"
"in vec4 col;"
"in vec2 pixel_pos;"
"in vec2 uv;"
"out vec4 o_col;"
"void main() {"
" o_col = texture(Tex, uv) * col;"
//" if (pixel_pos.x < ClipRect.x || pixel_pos.y < ClipRect.y || pixel_pos.x > ClipRect.z || pixel_pos.y > ClipRect.w) discard;" // Clipping: using discard
//" if (step(ClipRect.x,pixel_pos.x) * step(ClipRect.y,pixel_pos.y) * step(pixel_pos.x,ClipRect.z) * step(pixel_pos.y,ClipRect.w) < 1.0f) discard;" // Clipping: using discard and step
" o_col.w *= (step(ClipRect.x,pixel_pos.x) * step(ClipRect.y,pixel_pos.y) * step(pixel_pos.x,ClipRect.z) * step(pixel_pos.y,ClipRect.w));" // Clipping: branch-less, set alpha 0.0f
"}";
// GLFW callbacks to get events
static void glfw_error_callback(int error, const char* description)
{
@ -172,26 +116,14 @@ void InitGL()
if (!glfwInit())
exit(1);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_REFRESH_RATE, 60);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
window = glfwCreateWindow(1280, 720, "ImGui OpenGL example", NULL, NULL);
glfwMakeContextCurrent(window);
glfwSetKeyCallback(window, glfw_key_callback);
glfwSetScrollCallback(window, glfw_scroll_callback);
glfwSetCharCallback(window, glfw_char_callback);
glewExperimental = GL_TRUE;
glewInit();
// After calling glewInit() our GL error state may be GL_INVALID_ENUM
const GLenum err = glGetError();
(void)err;
IM_ASSERT(err == GL_NO_ERROR || err == GL_INVALID_ENUM);
}
void InitImGui()
@ -203,7 +135,7 @@ void InitImGui()
io.DisplaySize = ImVec2((float)w, (float)h); // Display size, in pixels. For clamping windows positions.
io.DeltaTime = 1.0f/60.0f; // Time elapsed since last frame, in seconds (in this sample app we'll override this every frame because our timestep is variable)
io.PixelCenterOffset = 0.5f; // Align OpenGL texels
io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB; // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array that we will update during the application lifetime.
io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB; // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;
io.KeyMap[ImGuiKey_UpArrow] = GLFW_KEY_UP;
@ -225,68 +157,11 @@ void InitImGui()
io.SetClipboardTextFn = ImImpl_SetClipboardTextFn;
io.GetClipboardTextFn = ImImpl_GetClipboardTextFn;
// Setup graphics backend
GLint status = GL_TRUE;
GLenum err = GL_NO_ERROR;
err = glGetError(); IM_ASSERT(err == GL_NO_ERROR);
// Create and compile the vertex shader
vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexSource, NULL);
glCompileShader(vertexShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);
if (status != GL_TRUE)
{
char buffer[512];
glGetShaderInfoLog(vertexShader, 1024, NULL, buffer);
printf("%s", buffer);
IM_ASSERT(status == GL_TRUE);
}
// Create and compile the fragment shader
fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
glCompileShader(fragmentShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);
IM_ASSERT(status == GL_TRUE);
// Link the vertex and fragment shader into a shader program
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glBindFragDataLocation(shaderProgram, 0, "o_col");
glLinkProgram(shaderProgram);
glGetProgramiv(shaderProgram, GL_LINK_STATUS, &status);
IM_ASSERT(status == GL_TRUE);
// Create Vertex Buffer Objects & Vertex Array Objects
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
GLint posAttrib = glGetAttribLocation(shaderProgram, "i_pos");
glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), 0);
glEnableVertexAttribArray(posAttrib);
GLint uvAttrib = glGetAttribLocation(shaderProgram, "i_uv");
glEnableVertexAttribArray(uvAttrib);
glVertexAttribPointer(uvAttrib, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (void*)(2*sizeof(float)));
GLint colAttrib = glGetAttribLocation(shaderProgram, "i_col");
glVertexAttribPointer(colAttrib, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (void*)(4*sizeof(float)));
glEnableVertexAttribArray(colAttrib);
err = glGetError(); IM_ASSERT(err == GL_NO_ERROR);
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
// Load font texture
glGenTextures(1, &fontTex);
glBindTexture(GL_TEXTURE_2D, fontTex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
const void* png_data;
unsigned int png_size;
ImGui::GetDefaultFontData(NULL, NULL, &png_data, &png_size);
@ -299,13 +174,6 @@ void InitImGui()
void Shutdown()
{
ImGui::Shutdown();
glDeleteProgram(shaderProgram);
glDeleteShader(fragmentShader);
glDeleteShader(vertexShader);
glDeleteBuffers(1, &vbo);
glDeleteVertexArrays(1, &vao);
glfwTerminate();
}
@ -368,6 +236,7 @@ int main(int argc, char** argv)
}
// 3) Rendering
glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
glClearColor(0.8f, 0.6f, 0.6f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
ImGui::Render();

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